Apparatus for heat dissipation of transforming radiators

ABSTRACT

In accordance with one embodiment of the present invention, a panel for a transformer radiator includes a pair of substantially-rectangular panel sheets joined together to form a plurality of internal fluid channels, each fluid channel including an inlet and an outlet, and a plurality of pin fins disposed on at least a portion of at least one external surface of the panel sheets.

FIELD OF THE INVENTION

The present invention relates generally to transformers. In particularthe present invention relates to heat dissipation for transformers.

BACKGROUND OF THE INVENTION

The power generation industry relies heavily on large transformers.Typically, these large transformers create enormous amounts of heat andrequire efficient cooling thereof to prevent failure. Generally, acoolant such as oil, is provided in the transformer tank to absorb theheat. The oil is circulated through numerous heat exchangers also knownas panels, that are in fluid communication with the transformer tank tocool the transformer. In the past, to provide better heat transfer, thenumber and size of the heat panels had been increased. However this isnot cost effective because of the cost of the oil and the raw materialsrequired to manufacture the panels.

Another manner of cooling the transformers includes ambient air flowingacross the panels known as natural convection. However, this type ofcooling can be problematic because of seasonal and geographic variationsin ambient conditions. To somewhat overcome this challenge, largeindustrial fans are utilized to force the air to move more quicklyacross the panels to dissipate the heat faster, known as forced airconvection. However, these fans are extremely loud, causing a greatmajority of the noise associated with substations, require a great dealof energy to operate, and require a great deal of maintenance.

Thus, it is desirable to provide a more efficient manner of coolingtransformers. It is also desirable to reduce the size of the transformerpanels to reduce the cost of raw materials and as well as the cost ofthe oil coolant. Lastly, it is also desirable to reduce or eliminate thenoise associated with the large fans while lowering manufacturing andmaintenance costs.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the presentinvention, wherein in one aspect an apparatus is provided that in someembodiments reduces the number and size of the panels, reduces noise andeffectively cools the transformers.

In accordance with one embodiment of the present invention, a panel fora transformer radiator includes a pair of substantially-rectangularpanel sheets joined together to form a plurality of internal fluidchannels, each fluid channel including an inlet and an outlet, and aplurality of pin fins disposed on at least a portion of at least oneexternal surface of the panel sheets.

In accordance with another embodiment of the present invention, atransformer radiator, includes a distributor header fluidly-coupled to atransformer, a collector header fluidly-coupled to the transformer, aplurality of panels, each panel having a pair ofsubstantially-rectangular panel sheets joined together to form aplurality of internal fluid channels, each fluid channel including aninlet fluidly-coupled to the distributor header and an outletfluidly-coupled to the collector header, and a plurality of pin finsdisposed on at least a portion of at least one external surface of thepanel sheets.

In accordance with yet another embodiment of the present invention, atransformer radiator includes a distributor header fluidly-coupled to atransformer, a collector header fluidly-coupled to the transformer, aplurality of panels, each panel having a pair ofsubstantially-rectangular panel sheets joined together to form aplurality of internal fluid channels, each fluid channel including aninlet fluidly-coupled to the distributor header and an outletfluidly-coupled to the collector header, and means for radiating heatfrom at least a portion of at least one external surface of the panelsheets.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a transformer tank.

FIG. 2 is a side view of the transformer tank of FIG. 1.

FIG. 3 is a perspective view of a heat exchanger panel.

FIG. 4 is a cross sectional view of the heat exchanger panel of FIG. 3.

FIGS. 5, 6, and 7 are perspective views of portions of heat exchangerpanels according to embodiments of the present invention.

FIGS. 8 and 9 are perspective views of fine pin fins, according toembodiments of the present invention.

DETAILED DESCRIPTION

The invention will now be described with reference to the drawingfigures, in which like reference numerals refer to like partsthroughout. The foregoing needs are met, to a great extent, by thepresent invention that in some embodiments, reduces the number and sizeof the panels, reduces noise and effectively cools the transformers. Anapparatus and method are provided that increase the natural airconvection cooling of a transformer. Further, in an embodiment of thepresent invention, the size of the transformer panels is reduced,lowering costs of the raw materials.

The effectiveness of heat transfer for this particular applicationdepends on the resistance within the oil, resistance within the metalforming the panels and the resistance of the air flowing over thepanels. Because oil and air are in convective motion, their respectiveresistances are dependent on their respective heat transfercoefficients. The resistance of the metal panels depends on thethickness of the metal wall and the thermal conductivity of the metal.Thus, the total resistance of the panel with the oil flowing inside andthe air flowing outside is the sum of the resistances of the oil, theair and the metal.

By reducing the resistance of any or all of these components, theaverage temperature of the transformer can be reduced, increasing theefficiency of the transformer itself. Because the majority of the totalthermal resistance lies within the air phase, lowering the resistance ofthe air leads to more efficient heat transfer.

FIGS. 1 and 2 illustrate a transformer tank 10 as seen at a sub-station.The transformer tank 10 includes a tank body 12 that encloses thetransformer (not shown). External to the tank body 12 are banks ofpanels 16. The panels 18 are coupled at their tops and bottoms tofacilitate fluid communication between the inside of the tank body 12and the panels 18 through the use of distributor headers 20 andcollector headers 22.

The distributor header 20 is located above each set of panels 18 and thecollector header 22 is located below each set of panels 18. Oil withinthe tank body 12 absorbs heat generated from various parts of thetransformers such as core and coils, and rises to the top. Once the hotoil rises, it enters a distributor header conduit 24 connected to thedistributor header 20. The oil then flows down through the panels 18 andis cooled. The buoyancy driving force developed due to heat dissipation,from radiator panel surfaces, causes the cooler oil to flow down towardthe collector header 22 and is returned into the tank body 12 through acollector header conduit 26. The cool oil begins to absorb heat from thetransformer, rises and the cycle continues.

Due to the immense heat generated by the transformer, the panels 18 arevery large and numerous in order to provide as much surface area aspossible for natural and forced convection to remove the heat from theoil. The distributor header 20 and collector header 22 are connectedfluidly to each of the panels 18. The panels 18 are spaced a certaindistance apart to permit airflow between the panels 18.

FIGS. 3 and 4 are perspective views of a panel 18 and a cross sectionalview of a panel 18, respectively. Generally, the panels 18 aresubstantially rectangular in nature. The panels 18 include a first panelsheet 28 and a second panel sheet 30 joined, as by welding and the like,at their respective perimeters 32. The panels 18 can have openings (notshown) and the like disposed therein for fluid communication with thedistributor and collector headers, 20, 22, respectively. When joinedtogether at their perimeters 32, the first and second panel sheets 28,form an interior region 34 for the oil flow. The first and second panelsheets 28, 30 can be “crimped” or have contours or indentations 36formed thereon to define internal fluid channels for the oil. Here, theindentations constitute the sheets 28, 30 being brought toward eachother at various locations, along a length of the panel 18. The panelcontours are arcuate or semi-circular in shape. The sheets 28, 30 cometogether at certain contact points 38. These contact points 38 providestrength and integrity for the panels 18. Adjacent the interior region34, the indentations 36 do not contact, providing a space between thesheets 28, 30 for the oil to flow through. In this manner of providingindentations, general internal fluid channels are formed for the oil toflow through. Although a general description of panels is providedherein, any conceivable form of channels, indentations, contours and thelike can be formed with the panels and is within the scope of thisinvention. It is also possible to have no indentations, such that thepanels 18 are generally rectangular and have a smooth, planar surface.

FIGS. 5, 6, 7 are perspective views of a panel 18 having a plurality ofheat exchanger extensions or fine pin fins 40 disposed on the panel.These fine pin fins 40 are generally solid throughout, cylindrical innature and are coupled to either or both sides of the panels. The finepin fins 40 may be coupled using any means known, such as welding andthe like. However, there must be a very tight tolerance when couplingthe fine pin fins 40 to the first and second panel exteriors 28, 30 suchthat there is very little, if any, gap. Gaps can reduce the heattransfer ability of the fine pin fins 40, thereby reducing the overallefficiency of the panels. The fine pin fins 40 may also be formedintegrally with panels 18. Further, the fine pin fins 40 may be hollowtubes to facilitate the oil to enter the fine pin fins 40.

In an embodiment of the present invention, the fine pin fins 40 may bearranged at certain locations on the panels 18. As illustrated in FIG. 5the fine pin fins 40 may be disposed along an entire surface of a panel18. As illustrated in FIG. 6, the fine pin fins 40 may be arranged atonly a top location of the panels 18. Placing the fine pin fins 40 inthis manner is efficient for several reasons. First, the fine pin fins40 can be expensive to form and couple to the exteriors of the panels18. Thus, having the fine pin fins 40 at only a portion of the panels 18reduces costs associated with raw materials, as well as labor. Next,placing the pin fins 40 at the top of the panel 18 makes effective useof the thermal properties of the oil. Because oil and air rise as theyabsorb heat, the oil and air adjacent the panels 18 is hottest at thetop of the panels 18. Thus, greater heat dissipation is required at thetop of the panels 18. Therefore, disposing the pins 18 at the top allowsfor the greatest heat exchange possible. Further, as illustrated in FIG.7, the pin fins 40 can be disposed along a side of the panels 18. Thepin fins 40 can also be formed in rows of at least 3 pin fins 40. Thenumber, pattern, placement, etc., of the pin fins can vary. The externalpanel contours can alternate having rows of fine pin fins 40, forexample. Thus, placement of the pin fins 40 at various locations iscontemplated and within the scope of the present invention.

As shown in FIG. 8, the fine pin fins 40 are in a particular patternsuch that the pin fins 40 are spaced at a certain distance from eachother. However, as shown in FIG. 9 the pin fins 40 are placed in arandom fashion and are spaced at varying distances from each other. Itis preferred that the fine pin fins 40 are placed over about 5% of thepanel 18 surface area to achieve sufficient heat transfer.

The fine pin fins 40 are arranged perpendicular to the surface of thepanel 18 to facilitate the greatest heat transfer as the ends of thefine pin fins 40 have the greatest surface area contact with the panels18. However, it is also possible to have the fine pin fins 40 arrangedat various angles and configurations. It is preferred that the pin fins40 be formed of a highly conductive material such as copper, steel andthe like. Pin fin dimensions can be varied to optimize heat transfer. Itis preferred to create as large a surface area as possible. For example,it is preferred that the pin fins 40 are cylindrical, oval, rectangular,square, triangular or have a cross-sectional shape that maximizes thesurface area, such as a pentagon or star shape and the like. It is alsopreferred that the pins have a very small diameter, on the order ofabout 100 microns to about 1 cm. It is preferred that the length “l” ofthe pins is approximately up to a few cm long, such as from 1 cm toabout 10 cm. It is also preferred to place each pin a certain distancefrom another pin, so as to facilitate air flow between the pins. Thus,it is preferred that each pin be placed from another pin for a distanceof approximately 1 to 10 times the diameter θ of the fine pin fins.Thus, if the diameters is θ, the distance “d” is in the range of 10 to100. This range can be utilized in the stream-wise direction (top orbottom) as well as in the span-wise direction (side to side). Further itis preferred to place the pin fins 40 of opposing panels 18 a particulardistance from each other so as not to restrict air flow between thepanels 18. Distances are measured from center to center of the pin'scross section.

In an embodiment of the present invention, formation and placement ofthe pins results in numerous advantages. One advantage is that thepanel's dimensions can be reduced leading to lower costs in rawmaterials and in the amount of oil required to flow through the tank.The number of panels can also be reduced, further reducing cost.Additionally, the average temperature of the oil is reduced, allowingfor the transformer to perform for a longer period of time withoutdegradation of the oil and solid insulation inside the transformer.Further, as the drop in temperature as a function of distance along thepanel surface from top to bottom is steeper in the case of a panel withpin fins, compared to a panel without the pin fins, overall buoyancydriven driving force responsible for oil flow is enhanced, which leadsto faster oil flow and consequently lower oil phase heat transferresistance. Thus, the pin fins also contribute to lowering the thermalresistance of the oil as well as the air. Yet another advantage is thatthe need for fans is reduced or eliminated, leading to significant noisereduction. The decreased need for fans also leads to further costreduction because the need to manufacture, operate and maintain the fansis reduced.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

1. A panel for a transformer radiator, comprising: a pair ofsubstantially-rectangular panel sheets joined together to form aplurality of internal fluid channels, each fluid channel including aninlet and an outlet; and a plurality of pin fins disposed on at least aportion of at least one external surface of the panel sheets.
 2. Theradiator panel of claim 1, wherein each fluid channel is defined by apredetermined number of panel sheet contours.
 3. The radiator panel ofclaim 2, wherein the panel sheet contours are semi-circular in shape andthe pin fins are cylindrical in shape.
 4. The radiator panel of claim 2,wherein the pin fins are disposed along at least a portion of each panelsheet contour.
 5. The radiator panel of claim 2, wherein the pin finsare disposed along an upper portion of each panel sheet contour.
 6. Theradiator panel of claim 2, wherein the pin fins are disposed along thepanel sheet contours that define the fluid channel proximate to an edgeof the panel sheets.
 7. The radiator panel of claim 2, wherein the pinfins are disposed along the entire length of each panel sheet contour.8. The radiator panel of claim 2, wherein the pin fins are disposedalong the entire length of alternating panel sheet contours.
 9. Theradiator panel of claim 2, wherein the pin fins are disposed in rowsalong the entire length of each panel sheet contour, each row includingat least three pin fins.
 10. A transformer radiator, comprising: adistributor header fluidly-coupled to a transformer; a collector headerfluidly-coupled to the transformer; a plurality of panels, each panelincluding: a pair of substantially-rectangular panel sheets joinedtogether to form a plurality of internal fluid channels, each fluidchannel including an inlet fluidly-coupled to the distributor header andan outlet fluidly-coupled to the collector header; and a plurality ofpin fins disposed on at least a portion of at least one external surfaceof the panel sheets.
 11. The radiator of claim 10, wherein each fluidchannel is defined by a predetermined number of panel sheet contours.12. The radiator of claim 11, wherein the panel sheet contours aresemi-circular in shape and the pin fins are cylindrical in shape. 13.The radiator of claim 11, wherein the pin fins are disposed along atleast a portion of each panel sheet contour.
 14. The radiator of claim11, wherein the pin fins are disposed along an upper portion of eachpanel sheet contour.
 15. The radiator of claim 11, wherein the pin finsare disposed along the panel sheet contours that define the fluidchannel proximate to an edge of each panel.
 16. The radiator of claim11, wherein the pin fins are disposed along the entire length of eachpanel sheet contour.
 17. The radiator of claim 11, wherein the pin finsare disposed along the entire length of alternating panel sheetcontours.
 18. The radiator of claim 11, wherein the pin fins aredisposed in rows along the entire length of each panel sheet contour,each row including at least three pin fins.
 19. The radiator of claim11, wherein the pin fins are disposed on alternating panels.
 20. Atransformer radiator, comprising: a distributor header fluidly-coupledto a transformer; a collector header fluidly-coupled to the transformer;a plurality of panels, each panel including: a pair ofsubstantially-rectangular panel sheets joined together to form aplurality of internal fluid channels, each fluid channel including aninlet fluidly-coupled to the distributor header and an outletfluidly-coupled to the collector header; and means for radiating heatfrom at least a portion of at least one external surface of the panelsheets.